Eventually, as they would start developing on new platforms, revitalizing Apple's competitors, and so, after a while, people would notice that there is a better (and most probably cheaper) alternative.
If you want to make "user" apps (apps that average users, not computer nerds use), you have to go with Mac/Windows/iOS/Android/Web. None of them gives Linux a competitive advantage over other platforms.
Linux will never be mainstream[1]. It's an operating system for hackers by hackers. The sooner people accept that, the better.
[1]: I'm aware of Android. But that's not Linux. Just like iOS and OS X are not "Unix".
